Coronary artery bypass grafting (CABG) has traditionally been performed with the use of a cardiopulmonary bypass (CPB) machine to oxygenate and perfuse the body during surgery. Recently, techniques have been developed to allow for performing CABG without the use of CPB by stabilizing the epicardial surface of a beating heart at the coronary anastomotic site with a stabilizer, by contacting the surface of the beating heart with the stabilizer to render a portion of the surface surrounding a target surgical site relatively motionless, to allow placement of sutures through the graft vessel and recipient coronary artery at the target surgical site. This procedure may be performed through a full sternotomy, mini-sternotomy, thoracotomy or mini-thoracotomy, or less invasively through a port provided within the chest cavity of the patient, e.g., between the ribs or in a subxyphoid area, with or without the visual assistance of a thoracoscope.
Access to the left anterior descending (LAD) coronary artery is easily achieved by either a sternotomy or a thoracotomy. However, the patient typically requires bypass to multiple coronary arteries, including the circumflex artery (CxA) on the left lateral aspect of the heart, the right coronary artery (RCA) on the right lateral aspect of the heart, and the posterior descending artery (PDA) on the back side of the heart. It is very difficult to access the CxA, RCA, and PDA without a sternotomy, as the heart needs to be turned or tilted (or turned and tilted) significantly to reach its side or back, and with an intact sternum, insufficient space exists for these maneuvers. For example, the apex of the heart is generally lifted out of the body through a sternotomy in order to reach the PDA. Surgeons often place the patient in a Trendelenberg position, with the operating table tilted so that the patient's head lies lower than the feet with the patient in supine position, in order to assist with lifting the heart up and back.
An additional challenge to beating heart surgery is that some hearts do not tolerate manipulation well from a hemodynamic standpoint. The potential exists with current manipulation techniques to compress the heart (e.g., by pressing it with stabilization feet) or great vessels in such a way that hemodynamic function is compromised.
There is a need for a beating heart retraction apparatus capable of physically translating a beating heart from its natural resting place to a location better suited to surgical access, and then holding the beating heart in the latter location during surgery without compressing (or otherwise deforming) the heart or great vessels in such a way that hemodynamic function is compromised.
Typically, beating heart surgery has been accomplished through a partial sternotomy using pericardial sutures to retract the heart into the proper-position for surgery, and using a stabilization apparatus (e.g., stabilizing feet) to stabilize the portion of the heart surface to be operated on. Sometimes, surgery is performed on the properly positioned heart without using a stabilization apparatus.
However, conventional use of pericardial sutures for retraction of a beating heart has limitations and disadvantages including the following. It is inconvenient and potentially harmful to the patient to incise the pericardium and insert sutures along cut edges of the pericardium, and then exert tension on the sutures to move the heart together as a unit with the pericardium. When the sutures are pulled to lift the heart (with pericardium), compressive force exerted by the pericardium on at least one side of the heart sometimes constrains cardiac contraction and expansion.
There are three distinct stages involved in preparing an artery (on an organ) for anastomosis:
gross manipulation: the organ is physically translated from its natural resting place to a location better suited to surgical access;
artery presentation: the target artery on the organ is identified and the position of the organ is finely adjusted so that the target artery is approachable; and
artery stabilization: the target artery and surrounding tissues are immobilized, allowing fine surgical techniques on very small features.
One class of the stabilization devices commonly used to stabilize a target portion of a heart surface (a portion on which surgery is to be performed) are the stabilization devices that comprise rigid ((T-shaped or linear) structures lined with suction cups, such as those described in the article Borst et al., “Coronary Artery Bypass Grafting Without Cardiopulmonary Bypass and Without Interruption of Native Coronary Flow Using a Novel Anastomosis Site Restraining Device (“Octopus”), J. of the American College of Cardiology, Vol. 27, No. 6, pp. 1356-1364, May 1996, and in U.S. Pat. No. 6,334,843. The stabilization devices described are marketed by Medtronic, Inc. and are known as “Octopus” devices.
It has been proposed to use such an Octopus device to assist in repositioning the heart into a desired position for surgery (by holding the retracted heart in this position), as well as to stabilize a portion of the heart's surface following retraction (gross movement) of the heart. See, for example U.S. Pat. No. 6,334,843 and PCT International Application WO97/10753 (by Medtronic, Inc.) entitled “Method and Apparatus for Temporarily Immobilizing a Local Area of Tissue,” published Mar. 27, 1997, especially with reference to FIG. 33 thereof. However, no conventional Octopus device can support a beating heart with adequate compliance to allow normal heart beating movement, and instead each conventional Octopus device would exert compressive or twisting force on at least one side of the beating heart, thereby constraining cardiac contraction and expansion. Also, one of the small-diameter suction cups of a conventional Octopus device would be too small to reliably grip (and support) the heart without causing trauma to the heart surface. Thus, in order to reliably (but atraumatically) retract and support the heart in the retracted position, many small-diameter suction cups (supported on a rigid frame which frame is itself rigidly supported) need to exert suction simultaneously on the heart, which exacerbates the problem of constrained cardiac contraction and expansion due to the exertion of compressive or twisting force on the heart.
U.S. Pat. No. 5,799,661, which issued Sep. 1, 1998 to Boyd, et al. (and assigned to Heartport, Inc.) describes (with reference to FIGS. 33A-33C) a suction cup manipulator on a long shaft. The suction cup is to be attached to an arrested heart by suction, and the device is then manipulated to move the heart around in the chest cavity. A vacuum is applied to the cup to provide suction, and the vacuum is said preferably to have a value not less than −150 mmHg (to avoid tissue damage). The suction cup is made of “a soft, flexible elastomeric material such as silicone rubber, has a diameter of approximately 12 mm to 50 mm, and has a textured, high friction distal surface (for gripping the heart). The high friction can be achieved by a pattern of bumps or an absorbent high friction material (such as nonwoven polyester fabric). A disadvantage of the bumps is that they would likely cause trauma to the organ being manipulated (even with a vacuum in the preferred range).
U.S. Pat. No. 5,799,661 suggests without explanation that the suction cup is flexibly mounted to the distal end of a rigid shaft, but it is apparent from FIGS. 33A-33B that this simply means that the cup itself has some flexibility so that the cup can bend relative to the rigid shaft. U.S. Pat. No. 5,799,661 does not teach attaching the suction cup to the shaft by a joint which provides limited freedom to translate along a first axis and/or full (or at least limited) freedom to rotate about the first axis, but no significant freedom to translate in directions perpendicular to the first axis. Thus, the suction cup apparatus described in U.S. Pat. No. 5,799,611 is useful only to retract an arrested heart: not a beating heart or other moving organ since the suction cup apparatus of U.S. Pat. No. 5,799,611 does not have compliance to allow for normal organ movement such as a heart beat, and would instead exert compressive or twisting restraint forces on at least one side of the moving organ, thereby constraining cardiac contractility (contraction and expansion) or other normal organ movement.
U.S. Pat. No. 5,782,746, issued Jul. 21, 1998, discloses an annular suction device for immobilizing part of the surface of a heart during surgery. Although the device is said to allow the heart to beat in a “relatively normal” manner during surgery, “the device is rigidly mounted to a fixed mounting structure during surgery, and thus neither the device nor the part of the heart surface which it immobilizes would have freedom to move significantly relative to the mounting structure during surgery. The reference suggests positioning the device on the heart, applying vacuum to the device to cause it to exert suction on the heart, then moving the device to “partially” raise the heart, and then rigidly mounting the device to the fixed mounting structure so that the device supports the “partially raised” heart during surgery.
WO 97/26828 (Gentilli) discloses a laparascopic-endoscopic surgical instrument for grasping and handling parenchymatous and cavum organs. The instrument has a rigid tube with a suction cup provided at the proximal end of the tube. The suction cup is pivotally connect to the end of the tube by a flexible section and stray wires are axially provided along the rigid tube and connected to the suction cup so the orientation of the suction cup can be changed by operating the wires at the distal end of the rigid tube. The rigid tube is connected to a vacuum source at its distal end for application of vacuum to the suction cup. There is no disclosure as to use of the device for manipulating a heart. More importantly, there is no provision for allowing rotation of the organ once it has been grasped by the suction cup, nor is there any provision for even allowing axial movement of the organ once it has been grasped by the suction cup. Only pivoting of the suction cup is provided for and the purpose of such pivoting appears to be for remotely controlling the orientation of the suction cup to align it with the target organ before engaging the organ. Additionally, the flexible member biases the suction cup toward axial alignment with the rigid tube.